1. Field of the Invention
The invention relates to a press section for a machine for the production of a fibrous web, in particular a paper web. In particular it concerns a press section having two extended press nips, with each extended press nip being formed in a known way by a rotatable press roll and by a rotating flexible press member, which can be pressed against the press roll by means of a press shoe.
2. Description of Related Art
The special features of known long-nip presses are as follows: The press nip is areal, and not substantially linear as in conventional roll presses. As a result in the press nip the still wet paper web is subject to pressing pressure over a relatively long distance and its dewatering is consequently more intensive. Furthermore the pressure in the press nip does not occur suddenly, but it can be continuously brought from a lower value to a high value. There is consequently the danger of the paper web becoming crushed in the press nip.
In a previously suggested two-nip press section both long-nip presses are constructed as double felt presses. I.e., each time the paper web passes through each extended press nip between two felt belts. This arrangement has proved successful in machines for the manufacture of relatively thick paper webs (size: 100-200 g/m.sup.2). However satisfactory values for the dry solids content have not been achieved in the manufacture of relatively thin paper grades.